1. Field of the Invention
The present invention relates to a bowling pin and a manufacturing method of the same.
2. Description of the Related Art
The bowling is popularly enjoyed as a simple leisure and the bowling is also performed popularly in competitions.
With respect to a pin which is served for bowling, the property that the pin can be easily turned down when a ball hits the pin or other pin hits the pin is important. That is, provided that conditions such as an impact force, an impact angle and the like at the time of hitting are equal among pins, the pins must be uniformly turned down. Accordingly, in conformity with the international standard, the shape and the weight of the pin is strictly determined such that a height is 38 cm, a maximum diameter is 12 cm, a diameter of a bottom face is 6 cm, a weight is not less than 1417 g and not more than 1644 g, and the difference in weight among ten pins which are arranged on each lane is less than 113 g.
The bowling pin is also required to generate a dry sound peculiar to the pin which is generated when the ball hits the pin or the pins hit each other and to have durability which can withstand the repeated hitting. Accordingly, the bowling pin which covers a surface of a wooden core material with a synthetic resin layer has been used.
Further, on a surface of this wooden bowling pin, a display portion constituted of letters, patterns and the like is formed by baking.
The weight of the ball is approximately 7.52 kg at maximum and velocity attributed to throwing the ball is also added to the ball when the ball hits the pin and hence, the energy of the ball is extremely large. Accordingly, depending on the use frequency of the pins, the pins must be exchanged with new pins at an interval of about several months and hence, the period in which the pin can be used is relatively short under such circumstances.
Accordingly, as the core material of the bowling pin, use of a synthetic resin having the excellent durability is considered. However, the use of such a synthetic resin has several drawbacks. First of all, since the synthetic resin has a larger specific weight than wood and hence, when the bowling pin is manufactured in a prescribed shape, the weight of the bowling pin becomes excessively heavy. The second drawback is that the dry sound which is peculiar to the pins is not generated when the ball and the pin hit each other or the pins hit to each other.
Accordingly, there has been proposed an idea which is considered to solve the above-mentioned drawback by making the core material manufactured using the synthetic resin in a hollow shape. However, when a hard synthetic resin is applied to the surface of the core material manufactured in a hollow shape by insert molding, the core material cannot withstand high temperature and high pressure and is deformed whereby they cannot be used as products.
Further, when the ball hits the pin, when the bowling pins hit each other, or when the turned-down pins are reset, the display portion formed on the surface of the bowling pin receives a considerable impact and friction. Since the display portion constituted of letter, patterns and the like is formed by baking, the display portion is peeled off in a short period thus exhibiting the poor appearance. Accordingly, it is necessary to paint the bowling pin again or the bowling pins must be frequently exchanged with new bowling pins.
The present invention has been made in view of the above-mentioned drawbacks and it is an object of the present invention to provide a bowling pin which exhibits the excellent durability while satisfying conditions such as a shape and a weight which the bowling pin is required to satisfy, a dry sound which is generated at the time of hitting and the like and a manufacturing method thereof.
Further, it is an object of the present invention to provide a bowling pin which exhibits high durability by preventing peeling off of a display portion even when the display portion receives an impact or a friction and a manufacturing method thereof.